Accurate sensing of intracranial electrical activity, such as for determining epileptogenic foci or otherwise, may require use of a plurality of brain contacts. Epileptogenic mapping is one example of the use of electrical devices with tissue-engagement contacts. Examples of two kinds of intracranial electrical contact devices are depth probes and flexible flat surface members.
Depth probes, which may be referred to as “depth electrodes,” penetrate deep into the brain tissue. On the other hand, flexible flat surface members, including what are sometimes referred to as “strip” electrodes and “grid” electrodes, may be placed subdurally in direct contact with brain tissue at the surface of the brain.
Each of these different kinds of intracranial tissue-engagement members may have a plurality of electrodes which are separated from one another by a non-conductive material on which the electrodes are mounted. Separate thin insulated lead wires extend from the tissue-engagement member for each electrode. Such lead wires extend away from the tissue-engagement member to one or more connectors connecting the lead wires with individual conductors, for example, for distributing individual electrode circuits to monitoring or recording equipment.
Conventional connection systems such as those used with apparatus for monitoring brain tissue are not adapted for selective direct connection of probes and the like to individual conductors, such as for applying stimulation signals. Such conventional systems constrain a user, such as when it is desired to monitor or stimulate very small signals. Similarly, impedance mismatches can occur when a probe or the like is not properly placed. In addition, noise may be allowed to intrude as a result of inefficiencies and poor electrical design of such conventional systems, and logistical problems may be created, such as by use of adapters, extra wiring, etc. In another example, conventional systems may require disconnection of one piece of equipment (e.g., EEG) before being able to apply a stimulus to particular conductor(s), or may restrict a corresponding stimulation signal magnitude. Further, conventional systems are not adapted for use with magnetic resonance imaging (MRI) concurrently with epileptogenic monitoring. Disconnection of a first connector and connection of a second connector takes time, and creates the opportunity for error and equipment breakage. Additional problems with conventional systems may occur due to extra setup time, extra procedures and their resultant cost, setup complexity and resultant possibility for error such as incorrect hookup, additional problems of open circuits and short circuits, etc.